Question

use the references to access important values if needed for this question.
a 1.61 mol sample of kr gas is confined in a 38.2 liter container at 16.1 °c.
if the amount of gas is increased to 2.42 mol, holding the volume and temperature constant, the pressure will increase because:
(select all that apply.)
with more molecules per unit volume, the molecules hit the walls of the container more often.
with more molecules in the container, the molecules have higher average speeds.
with higher average speeds, on average the molecules hit the walls of the container with more force.
as the average speed increases, the number of molecule - wall collisions decreases.
none of the above

Explanation:

• According to the ideal gas law \(PV = nRT\), when \(V\) (volume) and \(T\) (temperature) are constant (\(R\) is a constant), \(P\propto n\) (pressure is proportional to the amount of gas in moles).
• The average speed of gas molecules is given by \(v_{avg}=\sqrt{\frac{8RT}{\pi M}}\), where \(M\) is the molar mass of the gas. Since \(T\) is constant, the average speed of \(Kr\) molecules does not change when \(n\) (amount of gas) changes.
• Pressure is related to the frequency and force of molecular collisions with the container walls. When \(n\) increases (more molecules in the same volume), the number of molecules per unit volume increases. This leads to more frequent collisions of molecules with the walls of the container.

Answer:

With more molecules per unit volume, the molecules hit the walls of the container more often.